Is there any games/engines that using OpenGEX (besides Terathon's engines)?
I'm googled about it, but don't find anything.

Fair point. All I find on google is the C4 Engine and the Tombstone Engine. Let me try to lay out the options:
1. Continue with proprietary reverse engineered NIF and bring the epxorters for the major 3d modelling tools up to working condition with it
2. Converge on OpenGEX and add necessary asset file formats for parts that are missing
3. Converge on GLTF2.0 and add necessary asset file formats for parts that are missing
4. Converge on OSGT and OSGB and add necessary asset file formats for parts that are missing
5. Create YAFF (yet another file format) where we promise to ourselves that it will be better than all other formats before and globally usable ( relevant xkcd -> https://xkcd.com/927/ )

Don't forget that the newer NIF (>=TES4) have havok data which can be used as well to influence the animation/rigging. Many people would love to see this.

So I think we may be converging on a decision here. It seems like we should focus on OSG (for extending format support based on our native renderer / new capabilities) and NIF (to extend to future bethesda titles / new capabilities).

I want to prioritize one and was leaning towards OSG. Do we think for extending past morrowind to oblvion / fallout 3 / skyrim etc., we should focus on NIF first? I know there is already another massive oblivion asset import thread with work on this so I could leverage that progress.

Further NIF support has additional benefits:
1) support for more modern NIF assets already created by modders
2) supports the eventual evolution of OpenMW running Oblivion/Skyrim/Fallout3/4/etc.
3) OpenMW is no longer dependent on Morrowind specific plugins for asset creation, meaning that modern tools can be used using the latest version of NIF (Skyrim/Fallout3/4).

Even if OSG gets animation support, it's usage will still be low in comparison to those modeling and exporting to NIF.

If you would still like to develop OSG further, please do... don't let me (or anyone else) stop you.

Even if OSG gets animation support, it's usage will still be low in comparison to those modeling and exporting to NIF.

If you would still like to develop OSG further, please do... don't let me (or anyone else) stop you.

I'm going to localize my efforts to animation portions of the formats we may want to use and experiment with OSG / OpenGEX / Oblivion and Skyrim compatible NIF. This will be a learning experience for me. Then I will come back with hopefully some more wisdom on the subject of creating assets in blender and then importing them into the engine using the various formats.